1. Field of the Invention
The invention describes new compositions of sunless tanning formulations that contain methylsulfonyl methane (MSM), also known as methylsulfonylmethane and as methyl sulfone, in combination with certain glycols to produce a darker, longer-lasting, natural-looking and low odor sunless tan.
2. Related Art
Sunless tanning, also called self-tanning, is the ability to impart a tan to fair or light skin without the use of sunlight. In order to achieve a tanned look or otherwise darken their skin, individuals can expose their skin to sunlight or a source of simulated sunlight, e.g., a solar simulator or ultraviolet lamps. For many individuals, such exposure will stimulate formation of new melanin pigment and retention or increased amount of melanin in the epidermis and produce a darkened skin color. However, some individuals find that such exposure does not produce the desired melanin formation and as a result the desired tan is not obtained. It is also well known that, as light skin humans age, the ability to produce melanin through ultraviolet light stimulation diminishes significantly. Additionally, exposure to the sun or a source of ultraviolet radiation can have deleterious effects for many individuals and can, in fact, cause sunburn, skin blistering, premature skin aging or skin cancer. Self-tanning or sunless tanning compositions offer a safe alternative and enable these individuals to obtain the desired tanned look.
Commercial sunless tanning formulations, using dihydroxyacetone [DHA], or DHA in combination with other reducing sugars such as 1,3,4-trihydroxy-2-butanone (erythrulose), applied locally to the skin, were developed for this purpose.
In U.S. Pat. No. 6,706,257, issued Mar. 16, 2004, McCook et al showed that sunless tanning compositions are substantially improved by adding methylsulfonyl methane [MSM] sequentially or simultaneously to compositions containing dihydroxyacetone. The McCook patent reference further shows that the enhancement of the DHA response is optimized by the inclusion of about 5% by weight of MSM to DHA sunless tanning compositions.
Prior to the McCook patent teaching, MSM had been used as a nutritional supplement when taken orally, as a topical and systemic anti-arthritis treatment and as a topical moisturizer or skin softener. The topical moisturizing or skin softening properties of MSM are described in several publications, e.g., by U.S. Pat. No. 4,296,130 to Herschler.